Sony 70-300mm F4.5-5.6G SSM II

70–300 mm F4.5–5.6 G SSM II Telephoto Zoom Lens.

An advanced optical design with Sony’s original Nano AR Coating technology effectively suppresses reflections for notably enhanced overall image quality and minimized aberration as well as high contrast for excellent resolution throughout the zoom range. AF tracking is approximately 4x faster than the previous model, and a new dust and moisture resistant design maximizes reliability. An excellent choice for outdoor sports and wildlife, while a 4 foot (1.2 meter) minimum focus makes it useful for portraits and flowers as well.

ED (Extra-low Dispersion) Glass / Super ED Glass.
As focal lengths get longer, lenses built with conventional optical glass have difficulties with chromatic aberration, and as a result images suffer from lower contrast, lower color quality, and lower resolution. To counter such problems, ED glass was developed and is included in select lenses. It dramatically improves chromatic aberration at telephoto ranges, and provides superior contrast across the entire image, even at large aperture settings. Super ED glass provides enhanced compensation for chromatic aberration.

SSM (Super Sonic Wave Motor)
SSM is a piezoelectric motor that contributes to smooth and silent AF operation. The motor produces high torque at slow rotation, and provides immediate start and stop responses. It is also extremely quiet, which helps keep autofocusing silent. Lenses that feature SSM also include a position-sensitive detector to directly detect the amount of lens rotation, a factor that improves AF precision overall.

Circular Aperture.
In general, if an aperture uses 7 or 9 aperture blades, then the shape of the aperture becomes a 7-sided or 9-sided polygon as the aperture is made smaller. However, this has a certain undesirable effect in that the defocusing of point light sources appears polygonal and not circular. a lenses overcome this problem through a unique design that keeps the aperture almost perfectly circular from its wide-open setting to when it is closed by 2 stops. Smoother, more natural defocusing can be obtained as a result.

Nano AR Coating.
Original Sony Nano AR Coating technology produces a lens coating that features a precisely defined regular nano-structure that allows accurate light transmission while effectively suppressing reflections that can cause flare and ghosting. The reflection suppression characteristics of the Nano AR Coating are superior to conventional anti-reflective coatings, including coatings that use an irregular nano-structure, providing a notable improvement in clarity, contrast, and overall image quality.